1. Field of the Invention
The present invention relates to an image processing method and device for transforming the image data representing an image recorded on a photosensitive material, such as a color negative film, and a color reversal film, on the basis of the characteristic curve of the photosensitive material, to obtain processed image data.
2. Description of the Prior Art
Up to now, analog printers which imprint an image recorded on such a photosensitive material as a color negative film and a color reversal film on a photographic paper have been used. With such an analog printer, when the image recorded on a photosensitive material is over-exposed or under-exposed, the over-exposure or under-exposure cannot be corrected, and thus it has only been possible to obtain a print image with a low quality. On the other hand, digital printers, which read an image recorded on a photosensitive material to obtain digital image data, and by exposing the photographic paper on the basis of this image data, provides a print image have been used in recent years. With such a digital printer, the characteristic curve expressing the characteristics of a photosensitive material is stored as a one-dimensional look-up table (one-dimensional LUT), and the image data expressed by the densities of the image recorded on the photosensitive material is transformed with this one-dimensional LUT for providing a gray level correction, and thus, the over-exposure and the under-exposure can be corrected, which allows a higher-quality print image to be obtained than with an analog printer.
On the other hand, the advance of silver halide emulsion technology has allowed development of photosensitive materials having an extremely high sensitivity in recent years. Such a photosensitive material with high sensitivity has a drawback of that it offers excellent characteristics immediately after the manufacture, but it is susceptible to deterioration with time, such as fog due to a rise in the density of the unexposed portion and reduction in sensitivity, being affected by natural radioactive radiation and storage conditions, such as temperature and humidity. For such a photosensitive material, if deteriorated, providing appropriate gray level correction and grainness suppression treatments can improve the quality of a print image. However, with the above-mentioned technique which provides gray level correction by transforming the image data on the basis of the one-dimensional LUT which is used in compensation for over-exposure and under-exposure, gray level correction cannot be provided for a photosensitive material which has deteriorated with time with respect to a density rise. Also, for grainness suppression, the effect on a photosensitive material which has deteriorated is insufficient, and thus improvement has been demanded.
Therefore, the technique has been proposed which records information representing the characteristics of a photosensitive material, such as a gray patch, on the photosensitive material itself at the time of manufacture or before the development treatment, and in obtaining image data with a digital printer, acquires data representing the information in this gray patch portion to estimate the characteristic curve for the photosensitive material on the basis of this data, providing image processing for the image data.
However, for the above-stated method, which records a gray patch on the photosensitive material, a separate device for reading the gray patch information in addition to the image information is required, and further, the density of the gray patch must be recorded and read with accuracy, which makes the reading device for reading the image information large-sized and complicated, and as a result, increases the cost. In addition, when there is a difference between the elapsed period of time from when the user photographed the image and that from when the gray patch was recorded, the gray level correction is affected by the latent image preservability, and thus on the basis of the gray patch, it is impossible to provide an accurate gray level correction. Especially when the gray patch was recorded immediately after the manufacture of a photosensitive material, there is a great difference in latent image elapsed period of time between the gray patch and the photographed image, and thus, gray level correction carried out on the basis of the gray patch will have a substantially lowered accuracy.
The image outputting method according to the present invention is an image processing method which transforms image data obtained by reading an image recorded on a photosensitive material with a set characteristic curve corresponding to the photosensitive material to obtain processed image data, comprising the steps of:
acquiring elapsed time information concerning the elapsed time for the photosensitive material from the photosensitive material;
modifying the optimum characteristic curve for the photosensitive material on the basis of the elapsed time information to calculate a modified characteristic curve; and
transforming the image data on the basis of the modified characteristic curve to obtain the processed image data.
Here, xe2x80x9ca set characteristic curve corresponding to a photosensitive materialxe2x80x9d refers to the characteristic curve expressing the relationship between the exposure and the density for a photosensitive material. With the present invention, the exposure and the density for this characteristic curve are related to the image data and the processed image data, respectively, for transforming the image data.
xe2x80x9cThe optimum characteristic curvexe2x80x9d refers to the characteristic curve expressing the relationship between the exposure and the density for a photosensitive material just after the manufacture, however, the term may refer to the characteristic curve for a photosensitive material at the time which can be regarded as that immediately after the manufacture (for example, at the time of shipment), although a certain period of time has elapsed from the manufacture.
xe2x80x9cElapsed time information concerning the elapsed time for a photosensitive materialxe2x80x9d includes information about the density of the unexposed portion of a photosensitive material, and the lot number of a photosensitive material. For the lot number of a photosensitive material, it is necessary to acquire information for relating the lot number to the date and time of manufacture of the photosensitive material having the lot number in advance. A photosensitive material may be provided with information allowing the date and time of manufacture of the photosensitive material to be identified (for example, information concerning the date of manufacture) so that it can be used as xe2x80x9celapsed time information concerning the elapsed time for a photosensitive materialxe2x80x9d.
With the image processing method according to the present invention, it is preferable to calculate the modified characteristic curve also on the basis of the characteristic curve after the lapse of a set period of time in addition to the optimum characteristic curve.
Here, xe2x80x9cthe characteristic curve after the lapse of a set period of timexe2x80x9d refers to the characteristic curve expressing the characteristics of a photosensitive material after the elapsed time period of one year or two years, for example.
It is preferable to provide grain suppression treatment for the processed image data in accordance with the breadth of the modification of the image information on the basis of the modified characteristic curve.
The image processing device according to the present invention is an image processing device which transforms image data obtained by reading an image recorded on a photosensitive material with a set characteristic curve corresponding to the photosensitive material to obtain processed image data, comprising:
an elapsed time information acquiring means for acquiring elapsed time information concerning the elapsed time for the photosensitive material from the photosensitive material;
a storing means which stores the optimum characteristic curve for the photosensitive material;
a modifying means for modifying the optimum characteristic curve on the basis of the elapsed time information to calculate a modified characteristic curve; and
a transforming means for transforming the image data on the basis of the modified characteristic curve to obtain the processed image data.
With the image processing device according to the present invention, it is preferable that the storing means further store a characteristic curve after the lapse of a set period of time; and
the modifying means be a means for calculating the modified characteristic curve also on the basis of the characteristic curve after the lapse of a set period of time in addition to the optimum characteristic curve.
Further, with the image processing device according to the present invention, it is preferable that it further comprise a grainness suppression treatment means for providing grainness suppression treatment for the processed image data in accordance with the breadth of the modification of the image information on the basis of the modified characteristic curve.
According to the present invention, from a photosensitive material, the elapsed time information for the photosensitive material is acquired, and on the basis of this elapsed time information, the optimum characteristic curve is modified to provide the modified characteristic curve, and thus, the processed image data which is provided by transforming the image data with this modified characteristic curve is that wherewith the deterioration with time of the photosensitive material is corrected. Therefore, the fog due to the rise in density and the deterioration of the sensitivity are reduced, and so, processed image data which allows reproduction of an image with a quality close to that by the proper exposure immediately after the manufacture can be obtained.
By obtaining the modified characteristic curve also on the basis of the characteristic curve after the time lapse in addition to the optimum characteristic curve, the modified characteristic curve which accommodates the deterioration with time of the photographic photosensitive material can be accurately produced, whereby processed image data which allows reproduction of an image with a quality close to that by the proper exposure immediately after the manufacture, being exactly compensated for the deterioration with time of the photographic photosensitive material can be obtained.
Further, if the breadth of the modification of the image data on the basis of the modified characteristic curve is great, there is a possibility of the grainness of the photographic photosensitive material also being enhanced, and so, with the present invention, grainness suppression treatment is provided for the image data in accordance with the breadth of the modification of the image data on the basis of the modified characteristic curve, so that processed image data which allows reproduction of a high-quality image with a suppressed grainness can be obtained.
The purpose of the present invention is to offer an image processing method and device which can provide a gray level correction which fully accommodates the deterioration with time of a photosensitive material.